Tightening instrument for orthopaedic surgery of the spine

Abstract

The tightening instrument is made up of two parts ( 2,4 ) joined to each other by means which are designed to automatically uncouple the said two parts ( 2,4 ) by shearing rupture of a pin ( 8 ) when a predetermined tightening torque is reached, a first ( 2 ) of the two parts being provided with a means ( 3 ) permitting driving, characterized in that the second ( 4 ) of the two parts is a rod whose end ( 5 ) opposite its tightening end ( 6 ) is adapted to be introduced into a complementary recess ( 7 ) formed in the first part ( 2 ), and in that the said end ( 5 ) includes an axial reservoir ( 15 ) for receiving the broken end section ( 18 ) of the pin ( 8 ).

1. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said fast body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein said first and second bodies have a longitudinal side; wherein said second body has a second passage that opens between the reservoir and the longitudinal side of said second body; wherein said first body has a first passage that opens between the second passage in said second body and the longitudinal side of said first body; and wherein said shear pin is inserted through the first and second passages; and further including a third body that is fixedly secured on the longitudinal side of said first or second body; said third body having a third passage therethrough that opens into said first and second passages; and wherein said shear pin is received inside the third passage. 
   
   
     2. The instrument of  claim 1 , including means for guiding and holding said shear pin within at least one of said passages. 
   
   
     3. The instrument of  claim 1 , further including a setscrew threadably engageable against said shear pin. 
   
   
     4. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having, a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, and wherein the reservoir of said second body includes a plurality of seats to accept the end section of said shear pin, and wherein said first body has a channel that opens to the distal end of said first body and a proximal end, and the channel in the first body is open between the proximal and distal ends of the said first body. 
   
   
     5. The instrument of  claim 4  wherein said first body has a channel that opens to the distal end of said first body, said instrument including means for indicating to the user that said channel and seat are coaxially aligned. 
   
   
     6. The instrument according to  claim 4  Wherein said first body has a channel that opens to the distal end of said first body, and wherein the channel in said first body is formed through a component made of a material that is harder than the material from which said shear pin is made. 
   
   
     7. The instrument of  claim 4  wherein said first body has a channel that opens to the distal end of said first body and a proximal end, and including means for closing the channel near the proximal end of said first body. 
   
   
     8. The instrument of  claim 4 , wherein said reservoir has an axial dimension, and said end section of said shear pin is smaller than said axial dimension of said reservoir, whereby said end section drops into said reservoir after said shear pin breaks. 
   
   
     9. The instrument of  claim 4 , wherein said shear pin is not coaxial with said common axis of rotation. 
   
   
     10. The instrument of  claim 4 , wherein after said shear pin breaks, a new end section of said shear pin is created, and said reservoir has a volume sufficient to hold a plurality of end sections of said shear pin. 
   
   
     11. The instrument of  claim 4 , wherein said first body has a channel that opens to the distal end of said first body, wherein the reservoir of said second body communicates with said channel; and wherein said shear pin is received with the channel of said first body and the seat in the reservoir of said second body. 
   
   
     12. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, and wherein the reservoir of said second body includes a plurality of seats to accept the end section of said shear pin, and wherein said first body has a channel that opens to the distal end of said first body, said instrument including a member inserted in the first body substantially perpendicular to the longitudinal axis of the of the shear pin; said member having an orifice therein which can be brought by the user into the channel, said instrument further including a spring maintaining the member in a normally closed position in which the channel and the orifice of the member are not in the continuation of each other. 
   
   
     13. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein said reservoir has a width dimension and said shear pin has a length greater than twice said width dimension, so that after said shear pin is broken and said end section is within said reservoir, a new end section of said shear pin is positioned in said reservoir so that said new end section can be broken from said shear pin. 
   
   
     14. The instrument of  claim 13 , wherein said first and second bodies have a longitudinal side; wherein said second body has a second passage that opens between the reservoir and the longitudinal side of said second body; wherein said first body has a first passage that opens between the second passage in said second body and the longitudinal side of said first body; and wherein said shear pin is inserted through the first and second passages. 
   
   
     15. The instrument of  claim 14 , including means for guiding and holding said shear pin within at least one of said passages. 
   
   
     16. The instrument of  claim 13 , wherein the reservoir of said second body includes a plurality of seats to accept the end section of said shear pin. 
   
   
     17. The instrument of  claim 16 , including means for indicating to the user that said channel and seat are coaxially aligned. 
   
   
     18. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein after said shear pin breaks, a new end section of said shear pin is created and is positioned in said reservoir so that said new end section can be broken from said shear pin, and said reservoir has a volume sufficient to hold a plurality of end sections of said shear pin. 
   
   
     19. The instrument of  claim 18 , wherein said first and second bodies have a longitudinal side; wherein said second body has a second passage that opens between the reservoir and the longitudinal side of said second body; wherein said first body has a first passage that opens between the second passage in said second body and the longitudinal side of said first body; and wherein said shear pin is inserted through the first and second passages. 
   
   
     20. The instrument of  claim 19 , including means for guiding and holding said shear pin within at least one of said passages. 
   
   
     21. The instrument of  claim 18 , wherein the reservoir of said second body includes a plurality of seats to accept the end section of said shear pin. 
   
   
     22. The instrument of  claim 21 , wherein said first body has a channel that opens to the distal end of said first body, said instrument including means for indicating to the user that said channel and seat are coaxially aligned. 
   
   
     23. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein said first and second bodies have a longitudinal side; wherein said second body has a second passage that opens between the reservoir and the longitudinal side of said second body; wherein said first body has a first passage that opens between the second passage in said second body and the longitudinal side of said first body; and wherein said shear pin is inserted through the first and second passages; and wherein said reservoir has a width dimension and said shear pin has a length greater than twice said width dimension, so that after said shear pin is broken and said end section is within said reservoir, a new end section of said shear pin can be positioned in said reservoir. 
   
   
     24. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein said first and second bodies have a longitudinal side; wherein said second body has a second passage that opens between the reservoir and the longitudinal side of said second body; wherein said first body has a first passage that opens between the second passage in said second body and the longitudinal side of said first body; and wherein said shear pin is inserted through the first and second passages, and wherein after said shear pin breaks, a new end section of said shear pin is created, and said reservoir has a volume sufficient to hold a plurality of end sections of said shear pin. 
   
   
     25. The instrument of  claim 24 , wherein said shear pin has a length such that when said end section is in said reservoir, an opposite portion of said shear pin is outside of said first body and said second body. 
   
   
     26. The instrument of  claim 24 , wherein said reservoir has an axial dimension, and said end section of said shear pin is smaller than said axial dimension of said reservoir, whereby said end section drops into said reservoir after said shear pin breaks. 
   
   
     27. The instrument of  claim 24 , wherein said shear pin is not coaxial with said common axis of rotation. 
   
   
     28. The instrument of  claim 24 , wherein said shear pin is parallel to and offset from said common axis of rotation. 
   
   
     29. The instrument of claim a  24 , wherein said shear pin is oriented substantially perpendicular to said common axis of rotation. 
   
   
     30. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, and wherein the reservoir of said second body includes a plurality of seats to accept the end section of said sheer pin, and wherein said shear pin is parallel to and offset front said common axis of rotation. 
   
   
     31. The instrument of  claim 30 , including means for indicating to the user that said channel and seat are coaxially aligned. 
   
   
     32. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, and wherein the reservoir of said second body includes a plurality of seats to accept the end section of said shear pin, wherein said reservoir has a width dimension and said shear pin has a length greater than twice said width dimension, so that after said shear pin is broken and said end section is within said reservoir, a new end section of said shear pin can be positioned in said reservoir. 
   
   
     33. The instrument of  claim 32 , including means for indicating to the user that said channel and seat are coaxially aligned. 
   
   
     34. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with, said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein said reservoir has an axial dimension, and said end section of said shear pin is smaller than said axial dimension of said reservoir, whereby said end section drops into said reservoir after said shear pin breaks; and wherein said first and second bodies have a longitudinal side, said first body has a first passage and said second body has a second passage, said shear pin being inserted through the first and second passages; and further including a third body that is fixedly secured on the longitudinal side of said first or second body; said third body having a third passage therethrough that opens into said first and second passages; and wherein said shear pin is received inside the third passage. 
   
   
     35. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein said shear pin is not coaxial with said common axis of rotation; and wherein said first and second bodies have a longitudinal side, said first body has a first passage and said second body has a second passage, said shear pin being inserted through the first and second passages; and further including a third body that is fixedly secured on the longitudinal side of said first or second body; said third body having a third passage therethrough that opens into said first and second passages; and wherein said shear pin is received inside the third passage. 
   
   
     36. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein said reservoir has a width dimension and said shear pin has a length greater than twice said width dimension, so that after said shear pin is broken and said end section is within said reservoir, a new end section of said shear pin can be positioned in said reservoir; and wherein said first and second bodies have a longitudinal side, said first body has a first passage and said second body has a second passage, said shear pin being inserted through the first and second passages; and further including a third body that is fixedly secured on the longitudinal side of said first or second body; said third body having a third passage therethrough that opens into said first and second passages; and wherein said shear pin is received inside the third passage. 
   
   
     37. An instrument for tightening bone screws into a patient during orthopedic surgery, comprising: a first body and a second body, said first and second bodies sharing a common axis of rotation; said first body having a distal end; said second body having a reservoir therein, said second body having a distal end having a profile to engage a bone screw; and a shear pin with an end section, said shear pin being inserted through said first and second bodies with said end section positioned at least partially in the reservoir of said second body, whereby the reservoir can receive said end section when said shear pin breaks, wherein after said shear pin breaks, a new end section of said shear pin is created, and said reservoir has a volume sufficient to hold a plurality of end sections of said shear pin; and wherein said first and second bodies have a longitudinal side, said first body has a first passage and said second body has a second passage, said shear pin being inserted through the first and second passages; and further including a third body that is fixedly secured on the longitudinal side of said first or second body; said third body having a third passage therethrough that opens into said first and second passages; and wherein said shear pin is received inside the third passage. 
   
   
     38. The instrument of  claim 24 , including means for guiding and holding said shear pin within at least one of said passages.